DE102005016940A1 - Method fop applying powder layers onto substrate has a reciprocating scraper to remove excess powder for recycling - Google Patents

Abstract

A method for applying powder onto a substrate, e.g. to produce three dimensional items secured by laser sintering, has a reciprocating scraper (8) to move excess powder to collecting systems (11) each side of the substrate holder. The item is built up in layers and the collected powder is recycled to the other side of the scraper while the dosing rate is adjusted to ensure an even coating. The powder is pre-warmed during dosing and is subsequently heated to the process temperature. The recycling means comprise two rotating cylinders rotating in opposite directions.

Description

The The present invention relates to a device and a Method for applying layers of a powdery material on a surface according to the preamble of claim 1 or 12 as well as on a Device for producing a three-dimensional object according to the Preamble of claim 19.

Such a device and such a method for applying layers of a powdery material are for example from DE 195 14 740 known. The Indian DE 195 14 740 A coater described for a laser sintering apparatus has a single blade that pushes a supply of material for a layer before applying a layer. The problem here is that the supply of material for one layer is either too low, so that a complete layer can not be applied in the working area (construction field), or the stock is larger than the amount required for a layer, so that then excess material pushed out of the work area to the outside. This excess material is no longer used for the application of another layer, so it must be collected in special collection containers and contributes to an increased material consumption.

From the EP 945 202 is a coater with two blades known. Like the one in the DE 195 14 740 In the case of described coaters, this coater also has the problem that, during the application of a layer, excess material is pushed out of the working area in front of the front blade in the direction of movement of the coater. This material pushed outwards by the blade is not used here for the application of another layer and therefore contributes to an increased material consumption as above.

The The material to be applied can be made of various materials, e.g. Polymers, metals, ceramics or composites. Depending on Material and process control in a device for producing a three-dimensional object can be a warming the layers are used. In this case, that may be in the edge area accumulated material depending on the material, especially when using of polymers during the production of a three-dimensional object are thermally damaged and for that Reuse becomes unusable.

Of the The present invention is therefore based on the object, a device and a method for applying layers of a powdery material provide with which the layers reliably and without loss of material can be applied.

The Task is fulfilled by a device or a method for applying layers a powdery one Material according to claim 1 or 12.

The Invention has the advantage that that of a blade of the coater while applying a layer of the work area pushed outward Material for the application of the next Layer is reused and therefore no material loss occurs.

at the use of a feeder, at the supply of material is interrupted in a feed area, when a predetermined amount of material in the feed area is present finds a self-regulating dosage of material supply even if the surplus material accumulating when applying a layer from the blade to the feed area promoted becomes.

One Another advantage of the invention is that the thermal Strain on the application of a layer as excess material is low.

If an increased Process temperature needed has the use of a material handling device with A heated tub has the advantage of having the material before it rests preheated as a layer and thus the construction time is shortened becomes.

at the use of a designed as a fluidizing device Material transport device, in which the fluidization by preheated gas takes place, there is the advantage that the fluidized powder is preheated and thus the construction time is shortened can be, if increased Process temperature needed becomes.

Further Features and Practices of Invention will become apparent from the description of embodiments with reference to the attached drawings.

From show the figures:

1 a schematic representation of a laser sintering device with the device according to the invention;

2 a schematic representation of a first embodiment of the device for applying layers of a powdery material;

3 - 5 the device for applying layers of a powdery material 2 in different phases of operation; and

6 a schematic representation of a second embodiment of the apparatus for applying layers of a powdery material.

1 shows a laser sintering device as an embodiment of an apparatus for producing a three-dimensional object, in which the device according to the invention and the inventive method are used. The laser sintering device has an upwardly open container 1 on. Zn the container 1 is a carrier 2 for carrying the object to be formed 3 intended. The carrier 2 is by means of a drive 4 in the container 1 in the vertical direction A movable up and down. The upper edge of the container 1 defines a work plane 5 (Construction site). Above the working level 5 is an irradiation device 6 arranged in the form of a laser, which emits a directed laser beam, which via a deflection device 7 to the working level 5 is distracted. Further, a coater 8th for applying a layer of a powder material to be solidified to the surface of the support 2 or a last solidified layer provided. The coater 8th is by means of a schematically indicated by the arrows B drive between two end positions on the working plane 5 movable back and forth. Through two material feeders 9 left and right of the construction site and two material handling facilities 11 the coater is made up of two powder reservoirs 10 fed.

The device also has one above the work plane 5 arranged heating device 12 for preheating a coated but not yet sintered powder layer to a suitable for solidification or sintering working temperature T _A on.

At a distance above the work plane 5 is an example designed as a pyrometer or IR camera temperature measuring device 13 provided for measuring the temperature of the last applied or uppermost powder layer in a measuring range 14 serves.

Through a process chamber 16 the construction field is completed by the environment. As a result, if necessary, the oxidation of the powder can be prevented.

A control and / or regulating device 17 serves to control and / or regulate the movement B of the coater 8th , the movement A of the wearer 2 , the power of the heater 12 , the performance of the irradiation device 6 and the deflection by the deflector 7 , This is the control and / or regulating device 17 with the drive of the coater 8th , the drive 4 , the heater 12 , the temperature measuring device 13 , the deflector 7 as well as with the irradiation device 6 connected.

2 shows a first embodiment of the device for applying layers of a powdery material.

The device 51 for applying a layer of the powdery material according to a first embodiment comprises a coater 52 , one as a conveyor roller 53 trained material transport device as well as a feed shaft 54 trained material supply on.

The coater 52 is above a work plane 55 (Construction field) between two end positions with a direction indicated by the arrow B drive back and forth. He has a blade 56 , a first actuator 57 and a second actuator 58 on.

The conveyor roller 53 has two around a common axis 59 rotatable blades 60 . 60 ' on. Perpendicular to the axis 59 is a cam disc 61 with two cams 61a and 61b firmly with the conveyor roller 53 connected.

With the cam disc 61 are with their respective first end two elongated connecting rods 62 . 62 ' eccentrically rotatably connected. At its other second end, the connecting rods 62 . 62 ' each a hook-shaped section 62a respectively. 62a ' on, each as a point of attack for the second actuator 58 the coater serves. The axes of rotation 63 . 63 ' to which the two connecting rods 62 . 62 ' relative to the cam plate 61 are rotatable, lie with the axis 59 in a plane and are parallel to the axis 59 , Between their first and second end have the connecting rods 62 . 62 ' one slot each 62b respectively. 62b ' on. The movement of the connecting rod 62 . 62 ' is through one in the two slots 62b . 62b ' inserted pin 64 guided, wherein the pin is immovable relative to the position of the conveying roller. The long holes 62b . 62b ' are designed such that the two hook-shaped sections 62a . 62a ' when turning the conveyor roller augrund the guide through the pin 64 not just parallel to the work plane 55 but also move up and down perpendicular to the working plane.

The conveyor roller is in one with a heater 66 heated tub 65 seen in the direction of movement B of the coater laterally from the working plane 55 arranged. This tub 65 is at the conveyor roller 53 adapted so that the ends of the blades 60 . 60 ' when turning the conveyor roller 53 inside the tub 65 move along the tub wall.

On the construction field 55 opposite side of the tub 65 is the feed chute 54 , The feed shaft 54 serves to the coater 52 To supply powder for producing a powder layer.

in the The operation of the above-described laser sintering apparatus will be described below according to a method according to a first embodiment to be discribed.

First, as in 2 represented by methods of the coater 52 parallel to the work plane 55 a first powder layer 71 on the carrier 2 or applied to a previously solidified layer. This is excess powder 72 from the blade 56 pushed out of the construction site.

In an in 2 illustrated phase of the operation of the device according to the first embodiment is the first blade 60 below the working level 55 and the coater moves to make a first layer 71 of the powdered material on the conveyor roller 53 to. Finally, the aforementioned excess material 72 from the blade 56 on the first shovel 60 pushed (for the sake of clarity is in 2 no powder is drawn in the material transport device).

In an in 3 illustrated phase of the operation of the device presses the coater with the first actuator 57 against the cam 61b and rotates until it reaches a first end position, the conveyor roller by an angle of about 20 ° -40 ° on. This will make powder on the first blade 60 on the side facing the site (building site side) of the blade 56 raised. When the coater is in the first end position, much of the powder is on the blade 60 (seen in a direction perpendicular to the working plane) above the level defined by the lower end of the blade. Simultaneously with the rotation of the feed roller, the hook-shaped portion 62a ' at one end of the connecting rod 62 ' relative to the work plane 55 raised. The apparatus is thus prepared to apply a next layer of powder by moving the coater in the direction away from the conveying roller to the second end position on the other side of the building field.

After applying the layer 71 the powdery material is solidified at the cross-section of the object in this layer corresponding locations by exposure to the laser in a conventional manner.

Decisive for the quality of the finished object is in particular that the temperature of the uppermost powder layer to be consolidated has a temperature in a certain range, the process window. Above this process window, the powder is already sintered without additional radiant energy, while at temperatures below the process window form tension in the solidified layer. In many cases, the so-called curl effect, in which the edges of the solidified layer bend or roll up, is attributed to a too low temperature of the uppermost powder layer. The powder layer applied with the coater therefore has to achieve good results, in particular to avoid distortions in the fabricated object, prior to solidification with the heater 12 be heated to a working temperature T _A within the process window.

For this purpose, after the application of the powder layer, the temperature of this layer with the temperature measuring device 13 measured. Depending on the measured temperature, the heating power of the heater 12 certainly. If the uppermost powder layer is heated to the working temperature T _A , the points corresponding to the cross section of the object in the layer of the building material are solidified by irradiation with the laser.

After solidification of a layer, the carrier 2 is lowered by a distance corresponding to the layer thickness and with the coater a new powder layer 73 on the previously laser-exposed layer 71 applied.

In an in 4 In the illustrated phase of operation, the coater 52 moves to produce a next layer of powder 73 from the conveyor roller 53 away in a direction parallel to the work plane 55 , In this case, the second actuating element presses 58 finally on the raised hook-shaped section 62a ' of the connecting rod 62 ' , This will be the connecting rod 62 ' in the direction of movement of the coater 52 taken along and the conveyor roller 53 continued to turn. The conveyor roller is rotated by an angle of about 140 ° -160 °. That is on the shovel 60 Any remaining excess powder becomes the feed area below the feed chute 54 transported from the feed area is simultaneously from the second blade 60 ' Powder from the feed area transported towards the construction field. The powder consumed from the feed area trickles out of the feed chute. If the feed area is filled up with powder, the after-trickling, ie the supply of powder from the feed chute, stops by itself. With the movement of the connecting rod 62 ' At this stage, the hook-shaped section lowers 62a ' back to the working level 55 until the second actuator no longer opposes it and the connecting rod 62 ' not further from the coater 52 is taken.

In 5 the device is shown in the phase of operation in which the coater 52 on the other, in the 2 to 5 not shown side of the construction field is located. The coater is unidirectional from the conveyor roller 53 away moves through the coater a layer up to the entire construction field 73 of the powdered material is applied. The conveyor roller 53 is at 180 ° in this phase compared to in 2 rotated position shown.

With the 2 to 5 the operation of the material handling equipment and the material supply equipment on a first side of the construction field has been described. On the other second side of the first opposite side of the construction field is a similar device consisting of conveyor roller, tub, feeder and connecting rods, which works the same as with 2 to 5 has been described above. To create a next layer, the coater 52 again as in 2 shown in the direction of the conveyor roller 53 moved.

Then the steps described above are repeated until the preparation the three-dimensional object is completed.

In 6 is a device 100 for applying layers of a powdery material according to a second embodiment.

The apparatus for repeatedly forming a powder layer according to a second embodiment has a coater 101 as a fluidizing device 102 trained material handling equipment and one with a closure 103 provided feeder 104 on.

The coater 101 is above a working level as in the first embodiment 107 between two end positions with a direction indicated by the arrow B drive back and forth. He has a blade 105 and an actuator 106 on.

The fluidizing device has a chamber 108 for preheating the nitrogen used for fluidization, a the chamber 108 upwards concluding Fluidisierungsblech 109 and one with a valve 112 provided supply line 111 for nitrogen in the chamber 108 on. To preheat the nitrogen is the chamber 108 with a heater 117 (eg a resistance heater with temperature control) provided. The fluidization sheet 109 is with a multitude of small openings 110 provided, which have a smaller diameter D than that of the powder grains used. A gas supply line 111 leads into the chamber 108 , wherein the supply of gas into the chamber via a valve 112 is controllable.

Above the fluidization plate is a material supply device 104 with a lock 103 educated. The closure 103 is formed and arranged such that it is in the process of the coater in its end position by the actuating element 106 pressed to the side and thus the Materialzuführein direction with an opening 116 is opened to a supply area located below the material feed device. This is the actuator 106 designed so that it does not come even when opening the shutter in the opening area of the material supply. In particular, the actuator presses when opening on the closure 103 in a direction perpendicular to the image plane of 6 seen behind or in front of the opening 116 of the container 104 on the lock 103 , The side is the closure by a spring 113 attached to a side wall which pushes the closure to the closed position when the actuator 106 not against the closure 103 suppressed.

On the other side of the construction field is mirror-symmetrical to the previous one described Materialzuführeinrichtung and fluidizing means a further second material feeding device and another second fluidizing device is provided.

In operation, first a first powder layer 115 to the working level 107 applied by the coater above the construction field parallel to the working plane 107 is moved in the direction of the material supply. In the process, excess powder from the construction field is directed outwards onto the fluidization plate 109 pushed. The coater is moved further into its final position and thus opens by pressing the actuating element 106 against the lock 103 the material supply device 104 from which then as long as powder nachrieselt in the feed below the material feeding until it is filled up and the Nachrieseln ends by itself. Subsequently, the coater is just moved from the end position so far that the material feed device again by the spring 113 and the closure 103 is closed.

By briefly opening the valve 112 and introducing nitrogen gas into the chamber 108 over the supply line 111 In this chamber, a pressure surge is generated, which is responsible for the discharge of preheated nitrogen from the openings 110 in the Pul ver over the Fluidisierungsblech 109 leads. Thereby, this powder is fluidized and flows through the gap between the blade and the fluidizing sheet from the supply area on one side of the blade 105 to the other side of the blade facing the building field. The coater is thus prepared for the application of a next layer of powder.

As in the first embodiment, the powder layer is formed in a manner known per se with the heater 12 preheated and solidified at the cross section of an object corresponding locations.

In the next step takes place after lowering the carrier 2 as in the first embodiment, applying a next powder layer to the working plane in the construction field by moving the coater from the first end position to the second end position on the other side of the construction field.

The operation of the second feed device and the second material transport device, like the previously described operation of FIG 6 illustrated devices.

Then the steps described above are repeated until the preparation the three-dimensional object is completed.

alternatives and modifications of the above-described devices and the above described methods are possible.

The Device according to the second embodiment was with a Fluidizing described, in which the fluidization tion by introducing preheated Nitrogen is reached. But the fluidization can also by Introducing a different gas. Another way, the To achieve fluidization is to vibrate the powder to move.

The Device according to the first and the second embodiment has been described that on both sides of the construction field the same material transport facilities and material feeders are provided. It is possible, however the devices according to the first and the second embodiment to combine with each other so that on one side of the Baufeldes a material transport device and a material feed according to the first embodiment is provided while on the other hand, a material handling device and a material supply according to the second embodiment is provided.

It is possible, too, as in the first and second embodiments on both sides the construction field a material transport device according to the invention provide, but only on one side of the construction field, a material feed provided. Accordingly, during operation of the material transport device on the side where the material feeder is located for two layers to provide sufficient amount of material. This modification allows a simpler and more compact design of the device.

The Invention has been described with reference to a laser sintering device, in which a laser was used as the radiation source. Every other radiation source, with the electromagnetic or particle radiation in the building material can be introduced is possible. Thus, e.g. a source of radiation for incoherent light radiation, for IR radiation, for X-rays or for electron radiation be used as a radiation source. Accordingly, a building material to be used, which are solidified with the respective radiation can.

alternative can the device of the invention for applying powder coatings also used in 3D printers be in which the powder layers at the cross section of the produced Object by selective application of a binder or adhesive be solidified.

at The device described above is used as a heater Infrared radiators described above the working plane. Other options, one to heat the last applied layer of the building material are conceivable. For example, can the circulation of warm air or nitrogen to preheat the Layer to be used over the freshly applied layer is passed.

The embodiment of a device for producing a three-dimensional object was provided with a heater for preheating a coated but not sintered powder layer to a suitable for solidification or sintering working temperature T _A and with a temperature measuring device for measuring the temperature of the last applied or top powder layer is used. Depending on the material used and the process control, it is possible to dispense with preheating the applied material layer in the device according to the invention for producing a three-dimensional object. Accordingly, the device for producing a three-dimensional object can also be designed without a heating device and without a temperature measuring device.

The second embodiment has been described as performing the fluidization with preheated gas. However, it is also possible to realize the fluidization with non-preheated gas. Accordingly, the fluidizing means need not necessarily have a heater for preheating the gas used for fluidization.

Claims (19)

Device for applying layers of a powdery material ( 71 . 73 ; 115 ) with a coater ( 8th ; 52 ; 101 ), which is used to apply a layer of material ( 71 . 73 ; 115 ) is movable back and forth between two end positions and a blade ( 56 ; 105 ) for the removal of excess material ( 72 ) when creating a material layer ( 71 . 73 ; 115 ), characterized by a material transport device ( 11 ; 53 ; 102 ), with the material from one side of the blade ( 56 ; 105 ) can be transported to the other side of the blade. Apparatus according to claim 1, further comprising a material supply device ( 9 . 10 ; 54 ; 104 ) the a reservoir ( 10 ) for the material and is designed so that the supply of material is automatically interrupted in a feed area when in the feed area a predetermined amount of the material is present. Apparatus according to claim 1 or 2, wherein the material transport device ( 11 ) one around an axis ( 59 ) rotatable conveyor roller ( 53 ) for transporting material from one side to the other side of the blade ( 56 ) having. Apparatus according to claim 3, in which a mechanism ( 61 . 62 . 62 ' . 63 . 63 ' . 64 ) is provided, with which the movement (B) of the coater ( 52 ) to the rotation of the conveyor roller ( 53 ), that when the coater is moved once 52 ) Material with the conveyor roller ( 53 ) from one side of the blade ( 56 ) on the other side of the blade ( 56 ) is transported. Apparatus according to claim 3 or 4, wherein the conveyor roller ( 53 ) two to the axis of rotation of the conveyor roller ( 53 ) mirror-symmetrical blades ( 60 . 60 ' ) having. Device according to one of claims 3 to 5, wherein the conveying roller ( 53 ) is a roller with at least one recess formed as a chamber, can be transported by rotating the roller material by means of the chamber from one side to the other side of the blade. Device according to one of claims 3 to 6, wherein a tub ( 65 ) is provided, which is adapted to the shape of the conveying roller and receives a part of the conveying roller. Apparatus according to claim 7, wherein the tub ( 65 ) a heater for preheating the material in the tub ( 65 ) having. Apparatus according to claim 1 or 2, wherein the transport device ( 11 ) a fluidizing device ( 102 ), with which gas can be injected into the material such that the material fluidizes and from one side to the other side of the blade ( 105 ) flows when the coater ( 101 ) is in a predetermined position. Apparatus according to claim 1 or 2, wherein the transport device ( 11 ) is a fluidizing means for causing the material to vibrate such that the material fluidizes and flows from one side to the other side of the blade when the coater is in a predetermined position. Device according to one of claims 1 to 10, wherein on the two sides of the construction field, which correspond to the two end posi tion of the coater, each a transport device ( 11 ; 53 ; 102 ) is provided. Process for applying layers of a powdery material ( 71 . 73 ; 115 ) with a coater ( 52 ; 101 ), which is movable between two end positions for applying a layer of material, and a blade ( 56 ; 101 ), comprising the step of: (a) applying a layer of material to the coater ( 52 ; 101 ) on a surface, wherein the blade thereby the excess material ( 72 ) and from the construction field ( 55 ) pushes; characterized in that the method further comprises the step of: (b) transporting material from one side facing away from the building field to the other side of the blade of the coater facing the building field; The method of claim 12, wherein material from a reservoir ( 10 ) by a material feed device ( 54 ; 104 ) in a feed area next to the construction field ( 55 ; 107 ) is supplied. The method of claim 13, wherein in step (b) the material from the feed area on the building site ( 55 ; 107 ) facing away from the other side facing the work area of the blade ( 56 ; 105 ) of the coater located in an end position or near an end position ( 52 ; 101 ) is transported. The method of claim 13 or 14, wherein in step (a) the excess material ( 72 ) of the blade ( 56 ; 105 ) is pushed into the feed area. A method according to any one of claims 13 to 15, wherein the feeding of Material in the feed area is stopped as soon as a predetermined in the feed Amount of material is located. Method according to one of claims 12 to 16, wherein the transport of the material in step (b) by a rotatable conveying roller ( 53 ) he follows. Method according to one of claims 12 to 16, wherein the transport of the material in step (b) by a fluidization of the material by means of a fluidization device ( 102 ) he follows. Device for producing a three-dimensional Object by solidifying layers of a material to the respective cross section of the object corresponding points with a Apparatus for applying layers of a powdery material according to one of the claims 1 to 11.